Peripheral myopization and visual performance with experimental rigid gas permeable and soft contact lens design

PurposeTo evaluate the performance of two experimental contact lenses (CL) designed to induce relative peripheral myopic defocus in myopic eyes.MethodsTen right eyes of 10 subjects were fitted with three different CL: a soft experimental lens (ExpSCL), a rigid gas permeable experimental lens (ExpRGP) and a standard RGP lens made of the same material (StdRGP). Central and peripheral refraction was measured using a Grand Seiko open-field autorefractometer across the central 60° of the horizontal visual field. Ocular aberrations were measured with a Hartman-Shack aberrometer, and monocular contrast sensitivity function (CSF) was measured with a VCTS6500 without and with the three contact lenses.ResultsBoth experimental lenses were able to increase significantly the relative peripheral myopic defocus up to −0.50 D in the nasal field and −1.00 D in the temporal field (p < 0.05). The ExpRGP induced a significantly higher myopic defocus in the temporal field compared to the ExpSCL. ExpSCL induced significantly lower levels of Spherical-like HOA than ExpRGP for the 5 mm pupil size (p < 0.05). Both experimental lenses kept CSF within normal limits without any statistically significant change from baseline (p > 0.05).ConclusionsRGP lens design seems to be more effective to induce a significant myopic change in the relative peripheral refractive error. Both lenses preserve a good visual performance. The worsened optical quality observed in ExpRGP was due to an increased coma-like and spherical-like HOA. However, no impact on the visual quality as measured by CSF was observed.     

The effect of tinted soft contact lens wear on functional visual acuity and higher-order aberrations

PurposeTo investigate the differences of functional visual acuity (FVA) and high order aberrations (HOAs) in relation to tinted and clear hydrogel soft contact lens (SCL) wear.MethodsA prospective comparative study was performed in 16 eyes of 16 healthy volunteers. Dynamic visual acuity (using a FVA measurement system) and higher-order aberrations (using a wavefront sensor) were compared in subjects wearing two types of soft contact lenses: 1-day Acuvue^® (Vistakon, Jacksonville, FL) clear and the 1-day Acuvue^® Define^TM (Vistakon, Jacksonville, FL) tinted lens. The blink rates were recorded during FVA testing. The correlation between the difference of HOAs and differences in FVA values was analyzed.ResultsThe mean LogMAR FVA scores with clear and tinted SCLs were 0.07 ± 0.13 and 0.14 ± 0.17 (P < 0.05). The mean blink frequencies with clear and tinted SCL wear were 18.4 ± 8.3 and 25.3 ± 4.7 blinks/min (P < 0.05). Both 3rd-order aberrations and total HOAs showed statistically significant differences between the two types of soft contact lenses for 6 mm pupil measurements (P < 0.05). A significant positive linear correlation was observed between ΔHOAs and ΔLogMAR FVA for 6 mm pupil measurements (R = 0.53, P = 0.04).ConclusionsTinted contact lens wear appears to induce a reduction in optical quality. Functional visual acuity measurement is a useful procedure to study the changes of visual performance and quality in tinted contact lens wear.     

Which soft contact lens power is better for piggyback fitting in keratoconus?

PurposeTo evaluate the impact of differente soft contact lens power in the anterior corneal curvature and regularity in subjects with keratoconus.MethodsNineteen subjects (30 eyes) with keratoconus were included in the study. Six corneal topographies were taken with Pentacam Eye System over the naked eye and successively with soft lens (Senofilcon A) powers of −3.00, −1.50, 0.00, +1.50 and +3.00 D. Corneal measurements of mean central keratometry (MCK), maximum tangential curvature (TK), maximum front elevation (MFE) and eccentricity (Ecc) at 6 and 8 mm diameters as well as anterior corneal surface high order aberrations (i.e. total RMS, spherical- and coma-like and secondary astigmatism) were evaluated.ResultsNegative- and plano-powered soft lenses flattened (p < 0.05 in all cases), whereas positive-powered lenses did not induce any significant changes (p > 0.05 in all cases) in MCK in comparison to the naked eye. The TK power decreased with negative lenses (p < 0.05 in both cases) and increased with +3.00 D lenses (p = 0.03) in comparison to the naked eye. No statistically significant differences were found in MFE with any soft lens power in comparison to the naked eye (p > 0.05 in all cases). Corneal eccentricity increased at 8 mm diameter for all lens powers (p < 0.05 in all cases). No statistically differences were found in HOA RMS and spherical-like aberration (both p > 0.05). Statistically differences were found in coma-like and secondary astigmatism (both p < 0.05).ConclusionNegative-powered soft contact lenses provide a flatter anterior surface in comparison to positive-powered lenses in subjects with keratoconus and thus they might be more suitable for piggyback contact lens fitting.     

Efficacy of spherical aberration correction based on contact lens power

PurposeTo investigate the efficacy of spherical aberration (SA) correction with aspheric contact lenses (aspheric lenses) based on lens power, and compare the results with those of spherical contact lenses (spherical lenses).MethodsOcular higher-order aberrations were measured with a wavefront sensor, in 11 myopic subjects wearing an aspheric lens (Medalist Fresh fit (PUREVISION 2 HD); Bausch + Lomb) or a spherical lens (ACUVUE Oasys; Johnson & Johnson). Six different lens powers (−7.00 diopters (D), −5.00 D, −3.00 D, −1.00 D, +1.00 D, +3.00 D) were used for all subjects. The amount of SA correction from the contact lens at each power was calculated as the difference between SA with the contact lens on-eye and SA of the eye alone.ResultsFor the spherical lenses, SA correction was close to 0.00 μm for the +1.00 D lens, became more positive as the labeled lens power increased and became more negative as the labeled lens power decreased. For the aspheric lenses, SA correction was consistent, from −0.15 to −0.05 μm, for all lens powers except for the −1.00 D lens. SA correction for the spherical and aspheric lenses was significantly different at −7.00 D (p = 0.040), −3.00 D (p = 0.015), −1.00 D (p < 0.001), +1.00 D (p = 0.006), and +3.00 D (p < 0.001) powers.ConclusionAn aspheric lens is capable of correcting SA at different lens powers, and has SA correction in the range of −0.15 to −0.05 μm over a 6 mm aperture.     

Evaluating the effect of splitting cylindrical power on improving patient tolerance to toric lens misalignment

PurposeEvaluating the impact of splitting toric power on patient tolerance to misorientation such as with intraocular lens rotation.SettingUniversity vision clinic.MethodsHealthy, non astigmats had +1.50D astigmatism induced with spectacle lenses at 90°, 135°, 180° and +3.00D at 90°. Two correcting cylindrical lenses of the opposite sign and half the power each were subsequently added to the trial frame misaligned by 0°, 5° or 10° in a random order and misorientated from the initial axis in a clockwise direction by up to 15° in 5° steps. A second group of adapted astigmats with between 1.00 and 3.00DC had their astigmatism corrected with two toric spectacle lenses of half the power separated by 0°, 5° or 10° and misorientated from the initial axis in both directions by up to 15° in 5° steps. Distance, high contrast visual acuity was measured using a computerised test chart at each lens misalignment and misorientation.ResultsMisorientation of the split toric lenses caused a statistically significant drop in visual acuity (F = 70.341; p < 0.001). Comparatively better acuities were observed around 180°, as anticipated (F = 3.775; p = 0.035). Misaligning the split toric power produced no benefit in visual acuity retention with axis misorientation when subjects had astigmatism induced with a low (F = 2.190, p = 0.129) or high cylinder (F = 0.491, p = 0.617) or in the adapted astigmats (F = 0.120, p = 0.887).ConclusionMisalignment of toric lens power split across the front and back lens surfaces had no beneficial effect on distance visual acuity, but also no negative effect.     

Ocular aberrations and visual function with multifocal versus single vision soft contact lenses

PurposeTo investigate differences in ocular aberrations induced by centre-near multifocal soft contact lenses (SCL) relative to single vision SCLs and their effect on contrast sensitivity function (CSF).MethodsOcular aberrometry was measured in 18 cyclopleged subjects (19–24 years) while wearing Ciba Air Optix low (AOlow) and high (AOhigh) add, Bausch & Lomb PureVision low (PVlow) and high (PVhigh) add multifocals, and a Bausch & Lomb PureVision single vision (PVsv) control with the same −3.00 D distance back vertex power. Zernike polynomials were scaled to 4, 5 and 6 mm pupils. CSF was measured at equivalent distances of 6 m, 1 m and 40 cm while fully corrected with spherical trial lenses at 6 m.ResultsAOlow, AOhigh and PVhigh induced a negative shift in primary spherical aberration (Z12) from PVsv and all multifocal SCLs induced a positive shift in secondary spherical aberration (Z24) (all p < 0.01), without significantly increasing coma. Area under the CSF (AUCSF) reduced at 40 cm for all multifocals relative to PVsv (p < 0.05), but was not significantly different at 6 m or 1 m. A moderate correlation (r = −0.80, p < 0.005) was found between changes in Z12 and AUCSF at 40 cm for AOhigh, with an increase in negative Z12 reducing multifocal-induced loss of CSF.ConclusionsCentre-near multifocal SCLs induced a negative shift in Z12 and a positive shift in Z24. Although CSF was unaffected at 6 m and 1 m it was reduced at 40 cm, possibly because changes in Z12 and Z24 were not great enough to induce a significant shift in centre of focus and increase in depth of field.     

A comparative study of visual function of young myopic adults wearing contact lenses vs. spectacles

PurposeTo evaluate the impact of contact lenses wear vs. spectacles wear on visual function of young adults with mild to moderate myopia.Methods57 students (27 male and 30 female) with a mean age of 23 years old participated in the study. Their mean best corrected visual acuity was 10/10 binocularly, all suffered from mild to moderate myopia (?3.75 sph/SD 1.25 sph) and they were both contact lenses and spectacles wearers. The VF-14 questionnaire was administered to assess the contact lenses wear vs. spectacles wear impact score on general daily living among the young individuals. It was used translated in Greek after following the ‘translation-back translation’ procedure.ResultsThe mean VF-14 score among spectacles and contact lenses wearers was 100 and 86.78 (SD 4.08) respectively. Although there was a significant difference between the two groups (p < 0.05), both scores were related to a satisfactory functional vision for daily living. The contact lenses wearers were facing difficulty especially while driving at night, seeing steps, as well as doing fine handwork (i.e. sewing, knitting or carpentry).ConclusionsThe use of both spectacles and contact lenses provides satisfactory visual functioning for daily activities in young individuals suffering from mild to moderate myopia. However, there is a spectacles’ wear superiority in personal satisfaction when compared to contact lenses.     

Efficacy of two silicone-hydrogel contact lenses for bandage use after photorefractive keratectomy

PurposeTo evaluate the efficacy of two silicone hydrogel (SiH) contact lenses, approved for continuous wear for one week, following photorefractive keratectomy (PRK).MethodsForty seven myopic patients (94 eyes) undergone bilateral PRK were enrolled in this prospective, double-masked, comparative study. One eye of each patient was fitted with a Lotrafilcon B lens (Ciba Vision, Duluth, US; 30-day recommended replacement) whereas the fellow eye was fitted with an Asmofilcon A lens (Menicon, Nagoya, Japan; 14-day recommended replacement). Epithelial defect size was assessed using slit lamp biomicroscopy on the day of surgery and at days 1–4 post-operatively. Uncorrected and best-corrected visual acuity and retinal straylight (C-Quant, Oculus Optigerate, Germany) were evaluated pre-operatively and one month post-operatively.ResultsAverage epithelial defect size for Asmofilcon A and Lotrafilcon B was 25.5 ± 11.0 mm² vs. 27.1 ± 9.9 mm² at day 1 (p = 0.007) and 6.3 ± 7.0 mm² vs. 9.2 ± 9.5 mm² at day 2 (p = 0.012) post-operatively. Re-epithelialization at day 3 was completed in 87.2% of the eyes fitted with Asmofilcon A lenses, compared to 74.5% with Lotrafilcon B lenses (p = 0.012). At the 3rd post-operative day 29.8% of re-epithelialized eyes showed irregular suture with Lotrafilcon B, compared to 12.8% eyes with Asmofilcon A lenses (p < 0.001). Finally, no statistically significant differences were found post-operatively between the two lenses retinal straylight (p = 0.98) and best-corrected visual acuity (p = 0.68).ConclusionsSiH lenses can be used as an effective bandage after PRK due to the limited time requested for achieving complete corneal re-epithelialization. Faster and smoother epithelial healing is provided with Asmofilcon A over Lotrafilcon B lenses.     

Utility of a semi-scleral contact lens design in the management of the irregular cornea

ObjectivesTo evaluate the utility of the Rose K2 XL semi-scleral contact lens (Menicon Co. Ltd., Nagoya, Japan) in the management of the irregular cornea.MethodsTwenty-seven subjects (34 eyes) with irregular corneas referred for contact lens fitting were evaluated. A diagnostic trial set was used in the fitting process. Once the trial lens was considered optimal, a final lens was ordered from the manufacturer with the necessary changes in power, edge lift and diameter. We analyzed visual acuity, number of lenses ordered and patients’ ability to wear and handle lenses.ResultsTwenty-three subjects (30 eyes) were fitted with the Rose K2 XL lens. Four subjects (4 eyes) decided not to conclude the fitting process for different reasons. Average logMAR visual acuity without correction and with the lens was 0.82 and 0.09, respectively (p < 0.001). An average of 1.4 ordered lenses (range 1–3) were necessary to achieve the optimal fit. Nineteen eyes (63%) were fitted with the first lens ordered. Three subjects (13%) had problems with lens handling, and three subjects (4 eyes) abandoned the wear of the lenses after three months due to discomfort (3 eyes) and unsatisfactory visual acuity (1 eye), respectively. Follow-up ranged from 6 to 9 months.ConclusionRose K2 XL semi-scleral contact lens provides good visual acuity and comfort in patients with irregular corneas.     

Comparison of visual acuity and higher-order aberrations after femtosecond lenticule extraction and small-incision lenticule extraction

PurposeTo compare postoperative visual acuity and higher-order aberrations (HOAs) after femtosecond lenticule extraction (FLEX) and after small-incision lenticule extraction (SMILE).MethodsMedical records of refractive lenticule extraction patients were retrospectively reviewed. Twenty patients were treated with FLEX. A comparable group of 20 SMILE patients were retrospectively identified. Only one eye of each patient was randomly chosen for the study. Visual acuity, subjective manifest refraction and corneal topography before and 6 months after the surgery were analyzed for both groups. Total HOAs, spherical aberrations, coma and trefoil were calculated from topography data over the 4- and 6-mm-diameter central corneal zone.ResultsThe mean preoperative SE was −4.03 ± 1.61 in the SMILE group and −4.46 ± 1.61 in the FLEX group. One year after surgery, the mean SE was −0.33 ± 0.25 in the SMILE group and −0.31 ± 0.41 in the FLEX group (p = 0.86). In the SMILE group a greater number of eyes were within ±0.50 D of the target refraction (95% versus 75%); however, the difference was not statistically significant (p = 0.18). Furthermore, 80% of FLEX eyes and 95% of SMILE eyes had an uncorrected distance visual acuity of 20/25 or better (p = 0.34). Total HOAs, spherical aberration, coma and trefoil increased postoperatively in both groups. However, there was no statistically significant difference between the groups preoperatively and postoperatively.ConclusionFLEX and SMILE result in comparable refractive results. In addition, corneal aberrations induced by different techniques of lenticule extraction seemed similar to each other.     

Spectral transmittance of UV-blocking soft contact lenses: A comparative study

BackgroundThree major parts of sunlight consist of visible, ultraviolet and infrared radiation. Exposure to ultraviolet radiation (UVR) can result in a spectrum of skin and ocular diseases. UV-blocking contact lenses help provide protection against harmful UV radiation. We studied the ultraviolet and visible light rays transmission in some soft UV-blocking contact lenses.Material and methodsFour available tinted soft lenses (Acuvue Moist, Zeiss CONTACT Day 30 Air spheric, Pretty Eyes and Sauflon 56 UV) have been evaluated for UV and visible transmission. One-way ANOVA testing was performed to establish is there a statistically significant difference between the UV regions and visible spectra means for the contact lenses (α = 0.05).ResultsPretty Eyes, Zeiss CONTACT, Acuvue Moist and Sauflon 56 UV showed UV-B transmittance value of 0.65%, 10.69%, 1.22%, and 5.78%, respectively. Pretty Eyes and Acuvue Moist had UV-A transmittance values of 32% and 34%, Sauflon 56 UV and Zeiss CONTACT had transmittance values of 48% and 43%, respectively. All of the studied lenses transmitted at least 94.6% on the visible spectrum. The results of the one-way ANOVA statistical analysis show that a statistically significant difference exists within the group of contact lenses tested for the visible (p < 0.001), UV-B (p < 0.001) and UV-A (p < 0.001) portions of the spectrum (α = 0.05).ConclusionAcuvue Moist has the best UV-blocking property and also visible transmission between other tested contact lenses in this study.     

Visual performance and patient satisfaction of multifocal contact lenses in eyes undergoing monofocal intraocular Lens implantation

PurposeTo assess visual performance and patient satisfaction of multifocal contact lenses in eyes having monofocal intraocular lens (IOL) implantation.MethodsWe prospectively assessed uncorrected visual acuity at all distances (0.3, 0.4, 0.5, 0.7, 1, and 5 m), higher-order aberrations (HOAs), objective scattering index (OSI), contrast sensitivity, and patient satisfaction, before and during multifocal contact lenses wear in IOL-implanted eyes.ResultsVisual acuity at 0.3, 0.4, 0.5, 0.7, 1, and 5 m during wearing multifocal contact lenses was 0.21 ± 0.08, 0.11 ± 0.06, 0.01 ± 0.08, -0.02 ± 0.10, -0.02 ± 0.08, and -0.01 ± 0.07, respectively. We found a significant improvement at near to intermediate distances (30, 40, and 50 cm), but no significant change at intermediate to far distances (70 cm, 1 m, and 5 m). Log contrast sensitivity significantly decreased at 6 and 12 cycles/degrees, but did not significantly change at 1.5, 3, and 18 cycles/degrees. Third-order aberrations significantly increased after CL treatment, but fourth-order aberrations or total higher-order aberrations did not significantly change during CL treatment. The OSI and log(s) did not significantly change during CL treatment. The patient satisfaction score for overall vision significantly improved during CL treatment.ConclusionsMultifocal contact lenses significantly improved visual acuity at near to intermediate distances, and subsequent patient satisfaction, even though contrast sensitivity function slightly decreased, suggesting its viability of presbyopic correction in monofocal IOL-implanted eyes.     

Corneal changes following short-term rigid contact lens wear

PurposeThe aim of this cross-over study was to investigate the changes in corneal thickness, anterior and posterior corneal topography, corneal refractive power and ocular wavefront aberrations, following the short term use of rigid contact lenses.MethodFourteen participants wore 4 different types of contact lenses (RGP lenses of 9.5 mm and 10.5 mm diameter, and for comparison a PMMA lens of 9.5 mm diameter and a soft silicone hydrogel lens) on 4 different days for a period of 8 h on each day. Measures were collected before and after contact lens wear and additionally on a baseline day.ResultsAnterior corneal curvature generally showed a flattening with both of the RGP lenses and a steepening with the PMMA lens. A significant negative correlation was found between the change in corneal swelling and central and peripheral posterior corneal curvature (all p ≤ 0.001). RGP contact lenses caused a significant decrease in corneal refractive power (hyperopic shift) of approximately 0.5 D. The PMMA contact lenses caused the greatest corneal swelling in both the central (27.92 ± 15.49 μm, p < 0.001) and peripheral (17.78 ± 12.11 μm, p = 0.001) corneal regions, a significant flattening of the posterior cornea and an increase in ocular aberrations (all p ≤ 0.05).ConclusionThe corneal swelling associated with RGP lenses was relatively minor, but there was slight central corneal flattening and a clinically significant hyperopic change in corneal refractive power after the first day of lens wear. The PMMA contact lenses resulted in significant corneal swelling and reduced optical performance of the cornea.     

An acute clinical comparison of corneal staining and comfort associated with contact lens care solutions

PurposeThis study compared the biocompatibility and comfort of 4 lens care solutions currently marketed in France.MethodsThis was a randomized, interventional, double-masked, single-center crossover study assessing balafilcon A silicone hydrogel contact lenses, bilaterally, straight from the blister pack solution (control) and pre-soaked in the following lens care solutions: Regard^® (containing sodium chlorite), ReNu^® (containing a PHMB [polyhexamethylene biguanide] derivative), CyClean™ and MeniCare™ Soft (both containing PHMB). Subjects were randomized to the order of test solution use. For each of the 5 solutions tested, subjects attended a baseline/lens dispensing visit and an intervention visit 2 h later. At both visits, evaluation included slit-lamp examination, corrected-distance visual acuity, corneal staining, and subject-assessed photophobia, ocular comfort, and ocular redness.ResultsThirty subjects were enrolled and 28 were evaluable. Corneal staining severity was significantly worse than baseline after 2 h of wearing lenses soaked in CyClean, MeniCare, or ReNu (P ≤ 0.001). The MeniCare group alone demonstrated a significant improvement in ocular comfort after 2 h of lens wear (P = 0.02). No group demonstrated significant changes in ocular redness or photophobia. Corrected-distance visual acuity was similar between baseline and intervention visits for each test solution. No adverse events were reported during the study.ConclusionsSilicone hydrogel contact lenses presoaked in lens solutions containing PHMB or a PHMB derivative produced an increase in corneal staining after 2 h of lens wear. The higher levels of corneal staining in the 2 solutions did not correlate with increased discomfort within this 2-h timeframe.     

Conjunctival UV autofluorescence – Prevalence and risk factors

PurposeAutofluorescence of ultraviolet (UV) light has been shown to occur in localised areas of the bulbar conjunctiva, which map to active cellular changes due to UV and environmental exposure. This study examined the presence of conjunctival UV autofluorescence in eye care practitioners (ECPs) across Europe and the Middle East and its associated risk factors.MethodImages were captured of 307 ECPs right eyes in the Czech Republic, Germany, Greece, Kuwait, Netherlands, Sweden, Switzerland, United Arab Emirates and the United Kingdom using a Nikon D100 camera and dual flash units through UV filters. UV autofluorescence was outlined using ImageJ software and the nasal and temporal area quantified. Subjects were required to complete a questionnaire on their demographics and lifestyle including general exposure to UV and refractive correction.ResultsAverage age of the subjects was 38.5 ± 12.2 years (range 19–68) and 39.7% were male. Sixty-two percent of eyes had some conjunctival damage as indicated by UV autofluorescence. The average area of damage was higher (p = 0.005) nasally (2.95 ± 4.52 mm²) than temporally (2.19 ± 4.17 mm²). The area of UV damage was not related to age (r = 0.03, p = 0.674), gender (p = 0.194), self-reported sun exposure lifestyle (p > 0.05), geographical location (p = 0174), sunglasses use (p > 0.05) or UV-blocking contact lens use (p > 0.05), although it was higher in those wearing contact lenses with minimal UV-blocking and no spectacles (p = 0.015). The area of UV damage was also less nasally in those who wore contact lenses and spectacles compared to those with no refractive correction use (p = 0.011 nasal; p = 0.958 temporal).ConclusionUV conjunctival damage is common even in Europe, Kuwait and UAE, and among ECPs. The area of damage appears to be linked with the use of refractive correction, with greater damage nasally than temporally which may be explained by the peripheral light focusing effect.     

Clinical performance and “ex vivo” dehydration of silicone hydrogel contact lenses with two new multipurpose solutions

PurposeTo compare the performance of two novel multipurpose disinfecting solutions (MPDS) in preventing silicone hydrogel contact lens dehydration, provide higher scores of subjective comfort and stable optical quality during a month of lens wear in neophyte volunteers.MethodThis is a prospective, double-blind, contralateral and randomised study involving the contra lateral use of Complete RevitaLens^® and Biotrue MPDS. Twenty-five neophytes wore Air Optix Aqua for 1 month. Volunteers were evaluated on day 1 and day 30 at 2 and 10 h after lens insertion. Tear film stability using Tearscope Plus (Keeler, UK), whole eye aberrations for 4.5 mm pupil size (IRx3, ImaginEyes, France) and subjective comfort (0–10 score) along with the dehydration values obtained with a gravimetric method were collected at each follow-up visit.ResultsNIBUT values decreased significantly with both care systems from baseline to 10 h visit on day 1 (p = 0.032 and 0.016, mean difference = −6.7 s and −7.0 s, for Complete Revitalens and Biotrue, respectively). Dehydration rates and ocular aberrations did not change significantly over the month of follow-up (p > 0.05, ANOVA with Bonferroni post hoc corrections), nor between visits within the same day (p > 0.05, paired sample T-test). End-of-day dryness sensation worsened similarly with both MPDS after 1 month (p = 0.021 and 0.005, mean difference = −1.4 and −1.3, for Complete Revitalens and Biotrue, respectively).ConclusionsRegardless of their different chemical compositions in terms of moisture additives both MPDS solutions evaluated performed similarly regarding objective measures of dehydration, tear stability and optical quality but presented significant differences in subjective symptoms.     

Kerasoft IC compared to Rose-K in the management of corneal ectasias

PurposeTo determine the efficacy of the KeraSoft^® IC (KIC) (Ultravision International Limited, Bedfordshire, UK), a silicone hydrogel contact lens, for the optical management of non-surgical corneal ectasias and to compare it with the Rose-K 2 RGP contact lens.MethodsIn a retrospective study ninety-four eyes fitted with KIC (group A) were compared with seventy-seven eyes fitted with Rose-K^® RGP lenses as a control group. Ocular diagnoses, corneal curvature by topography, refraction, best spectacle-corrected visual acuity (BSCVA), and age at time of fitting were noted. Outcome data included average daily wearing time, contact lens complications, visual acuity with the lens (BCLCVA), power of the lenses and length of follow-up.ResultsDifferences in either BCLCVA or wearing time could not be statistically established (p = 0.63, p = 0.15) between both groups. More biomicroscopic complications were found in the RGP group, basically corneal staining (P < 0.0001). In the KIC group, BCLCVA was statistically similar between types of ectasia (p = 0.19) as well as in mild and moderate keratoconus (p = 0.45).ConclusionsKIC is a good alternative for the optical management of irregular corneal astigmatism in non surgical corneal ectasias such as keratoconus and pellucid marginal degeneration.     

Corneal changes following short-term miniscleral contact lens wear

PurposeTo examine the influence of short-term miniscleral contact lens wear on corneal shape, thickness and anterior surface aberrations.MethodsScheimpflug imaging was captured before, immediately following and 3 h after a short period (3 h) of miniscleral contact lens wear for 10 young (mean 27 ± 5 years), healthy participants. Natural diurnal variations were considered by measuring baseline diurnal changes obtained on a separate control day without contact lens wear.ResultsSmall but significant anterior corneal flattening was observed immediately following lens removal (overall mean 0.02 ± 0.03 mm, p < 0.001) which returned to baseline levels 3 h after lens removal. During the 3 h recovery period significant corneal thinning (−13.4 ± 10.5 μm) and posterior surface flattening (0.03 ± 0.02 mm) were also observed (both p < 0.01). The magnitude of posterior corneal flattening during recovery correlated with the amount of corneal thinning (r = 0.69, p = 0.03). Central corneal clearance (maximum tear reservoir depth) was not associated with corneal swelling following lens removal (r = −0.24, p > 0.05). An increase in lower-order corneal astigmatism Z(2,2) was also observed following lens wear (mean −0.144 ± 0.075 μm, p = 0.02).ConclusionsFlattening of the anterior corneal surface was observed immediately following lens wear, while ‘rebound’ thinning and flattening of the posterior surface was evident following the recovery period. Modern miniscleral contact lenses that vault the cornea may slightly influence corneal shape and power but do not induce clinically significant corneal oedema during short-term wear.     

Lens parameter changes under in vitro and ex vivo conditions and their effect on the conjunctiva

PurposeTo quantify changes in contact lens parameters induced by lens wear and determine whether these changes are associated with contact lens-induced conjunctival staining (CLICS).MethodsIn vitro: Lens diameter, sag, edge shape, base curve of six contact lens brands (balafilcon, comfilcon, etafilcon, lotrafilcon B, omafilcon and senofilcon) measured at 21 °C and 35 °C (eye temperature). Ex vivo: Diameter of lenses collected from a prospective, randomised, contra-lateral, cross-over clinical trial from 36 subjects wearing all lens types for 1 week daily wear, measured in 35 °C PBS after removal. Ocular surface was examined for lens-induced conjunctival staining by masked examiner.ResultsIn vitro: Changes in diameter and base curve outside ISO tolerance were found with etafilcon A and omafilcon A. Ex vivo: Comfilcon A and etafilcon A had greatest shrinkage in diameter (0.18 mm) and base curve (0.11 mm steeper) with temperature increase from 21 °C to 35 °C. Senofilcon A, lotrafilcon B and balafilcon A maintained most stable parameters between 21 °C and 35 °C. Changes in diameter and base curve from lens wear were not correlated with CLICS (p > 0.49). Multivariate analysis showed significantly greater levels of lens induced staining were associated with lens modulus (p < 0.001) and knife (p < 0.001) and chisel (p < 0.001) edge shapes.ConclusionsParameter changes induced by lens wear were associated with increasing temperature, but these changes in lens diameter and base curve did not induce CLICS. Modulus and edge shape were associated with increased CLICS. The susceptibility of etafilcon A and omafilcon A lenses to parameter changes might be related to their high water content.